The present invention provides compounds, pharmaceutical compositions containing one or more of those compounds or their pharmaceutically acceptable salts, which are effective in inhibiting the binding of various chemokines, such as MIP-1α, leukotactin, MPIF-1 and RANTES, to the CCR1 receptor. As antagonists or modulators for the CCR1 receptor, the compounds and compositions have utility in treating inflammatory and immune disorder conditions and diseases.
Human health depends on the body's ability to detect and destroy foreign pathogens that might otherwise take valuable resources from the individual and/or induce illness. The immune system, which comprises leukocytes (white blood cells (WBCs): T and B lymphocytes, monocytes, macrophages granulocytes, NK cell, mast cells, dendritic cell, and immune derived cells (for example, osteoclasts)), lymphoid tissues and lymphoid vessels, is the body's defense system. To combat infection, white blood cells circulate throughout the body to detect pathogens. Once a pathogen is detected, innate immune cells and cytotoxic T cells in particular are recruited to the infection site to destroy the pathogen. Chemokines act as molecular beacons for the recruitment and activation of immune cells, such as lymphocytes, monocytes and granulocytes, identifying sites where pathogens exist.
Despite the immune system's regulation of pathogens, certain inappropriate chemokine signaling can develop and has been attributed to triggering or sustaining inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis and others. For example, in rheumatoid arthritis, unregulated chemokine accumulation in bone joints attracts and activates infiltrating macrophages and T-cells. The activities of these cells induce synovial cell proliferation that leads, at least in part, to inflammation and eventual bone and cartilage loss (see, DeVries, M. E., et al., Semin Immunol 11(2):95-104 (1999)). A hallmark of some demyelinating diseases such as multiple sclerosis is the chemokine-mediated monocyte/macrophage and T cell recruitment to the central nervous system (see, Kennedy, et al., J. Clin. Immunol. 19(5):273-279 (1999)). Chemokine recruitment of destructive WBCs to transplants has been implicated in their subsequent rejection. See, DeVries, M. E., et al., ibid. Because chemokines play pivotal roles in inflammation and lymphocyte development, the ability to specifically manipulate their activity has enormous impact on ameliorating and halting diseases that currently have no satisfactory treatment. In addition, transplant rejection may be minimized without the generalized and complicating effects of costly immunosuppressive pharmaceuticals.
Chemokines, a group of greater than 40 small peptides (7-10 kD), ligate receptors expressed primarily on WBCs or immune derived cells, and signal through G-protein-coupled signaling cascades to mediate their chemoattractant and chemostimulant functions. Receptors may bind more than one ligand; for example, the receptor CCR1 ligates RANTES (regulated on activation normal T cell expressed), MIP-1α (macrophage inflammatory protein), MPIF-1/CKβ8, and Leukotactin chemokines (among others with lesser affinities). To date, 24 chemokine receptors are known. The sheer number of chemokines, multiple ligand binding receptors, and different receptor profiles on immune cells allow for tightly controlled and specific immune responses. See, Rossi, et al., Ann. Rev. Immunol. 18(1):217-242 (2000). Chemokine activity can be controlled through the modulation of their corresponding receptors, treating related inflammatory and immunological diseases and enabling organ and tissue transplants.
The receptor CCR1 and its chemokine ligands, including, for example MIP-1α, MPIF-1/CKβ8, leukotactin and RANTES, represent significant therapeutic targets (see Saeki, et al., Current Pharmaceutical Design 9:1201-1208 (2003)) since they have been implicated in rheumatoid arthritis, transplant rejection (see, DeVries, M. E., et al., ibid. and Gao, et al., J. Clin. Investigation, 105:35-44 (2000)), and multiple sclerosis (see, Fischer, et al., J Neuroimmunol. 110(1-2):195-208 (2000); Izikson, et al., J. Exp. Med. 192(7):1075-1080 (2000); and Rottman, et al., Eur. J. Immunol. 30(8):2372-2377 (2000). In fact, function-blocking antibodies, modified chemokine receptor ligands and small organic compounds have been discovered, some of which have been successfully demonstrated to prevent or treat some chemokine-mediated diseases (reviewed in Rossi, et al., ibid.). Notably, in an experimental model of rheumatoid arthritis, disease development is diminished when a signaling-blocking, modified-RANTES ligand is administered (see Plater-Zyberk, et al., Immunol Lett. 57(1-3):117-120 (1997)). While function-blocking antibody and small peptide therapies are promising, they suffer from the perils of degradation, extremely short half-lives once administered, and prohibitive expense to develop and manufacture, characteristic of most proteins. Small organic compounds are preferable since they often have longer half lives in vivo, require fewer doses to be effective, can often be administered orally, and are consequently less expensive. Some organic antagonists of CCR1 have been previously described (see, Hesselgesser, et al., J. Biol. Chem. 273(25):15687-15692 (1998); Ng, et al., J. Med. Chem. 42(22):4680-4694 (1999); Liang, et al., J. Biol. Chem. 275(25):19000-19008 (2000); and Liang, et al., Eur. J. Pharmacol. 389(1):41-49 (2000)). In view of the effectiveness demonstrated for treatment of disease in animal models (see, Liang, et al., J. Biol. Chem. 275(25):19000-19008 (2000)), the search has continued to identify additional compounds that can be used in the treatment of diseases mediated by CCR1 signaling.
Additionally, a chemokine receptor antagonist/modulator can have beneficial effects in the prevention of progressive fibrosis, such as renal fibrosis (see Anders, et al., J. Clin. Investigation 109:251-259 (2002)) and/or pulmonary fibrosis (see Tokuda, et al., J. Immunol. 164:2745-2751 (2000)).
A chemokine receptor antagonist/modulator can also have beneficial effects in the treatment of cancer and/or in the prevention of cancer; for example. For example, this can occur by inhibiting any role of immune cells, such as macrophages, in contributing to tumor development (see Robinson, et al., Cancer Res. 63:8360-8365 (2003)).
The MCP-1 receptor CCR2b signals through a variety of G-proteins (see Monteclaro et al, J. Biol. Chem., 37, 23186 (1997). MCP-1 interaction with the CCR2b receptor leads to various biological effects including increased histamine release, calcium influx, cAMP activation and promotion of migration of circulating monocytes into tissues.
MCP-1 has been implicated in various human diseases, including atherosclerosis, multiple sclerosis, asthma and rheumatoid arthritis (for example see Aielo et al, Arteriosclero Throm Vasc Bio., 19, 1518, (1999) and Fuentes, J. Immunology, 155, 5769, (1995)) and various cell types including endothelial cells, smooth muscle cells, macrophages and fibroblasts produce MCP-1. Leukocyte entry into tissue involves chemotactic signaling to circulating cells, interaction with endothelial cells and transmigration through tissues. Additionally, in addition to acting as a chemoattractant, MCP-1 can further potentiate the inflammatory response by promoting integrin expression and cellular adhesion.
MCP-1 is expressed at sites of inflammation and autoimmune disease, and therefore compounds which inhibit the binding of MCP-1 to the chemokine CCR2 receptor will provide useful leads in the discovery of drugs that will inhibit the action of MCP-1 on target cells. Patent application WO 02/070523 provides a useful summary of known information in this regard. WO 02/070523 also summarises the underlying facts that homing and activation of eosinophils, basophils and memory CD4+ Th2+ lymphocytes in lung tissues are considered important to the etiology of chronic airway inflammatory diseases. Several chemokines have been shown to mediate the recruitment and activation of these cell types. Specifically, eotaxin, eotaxin 2, MCP-3, MCP-4 and Rantes are produced from human lung mast cells and other relevant cell types activate the aforementioned effector cells through binding to the CCR3 receptor. Potential therapeutic uses of CCR3 antagonists include asthma and COPD.